1. Field of the Invention
This invention relates generally to pallet assembly operations and more particularly to an apparatus and method which utilizes a pivotable table for fabrication of pallets.
2. Discussion of the Prior Art
Pallets used for the storing and shipment of goods typically have a top and bottom deck with at least two so-called stringers extending therebetween. Such pallets have been used for many years to permit the handling of loads with fork trucks having forks which extend between the two decks of the pallet. The pallet decks are constructed of wooden boards, with the stringers extending in a direction normal to the boards. Various systems have been developed for assembling pallets without requiring a high degree of skill or substantial expenditure of time by the laborer.
The earliest such systems consisted of simple jigs designed to facilitate alignment of the deck boards and stringers during assembly. While jigs are helpful in reducing the amount of skill required to assemble a pallet, it was still quite time consuming to fabricate pallets in this fashion.
In an attempt to reduce the labor costs associated with pallet assembly, various attempts have been made to develop automatic machines for assembling pallets. One such machine is disclosed in U.S. Pat. No. 3,968,560 to Vial. Another automated system is being marketed by John L. Johnson & Associates of Portland, Oregon, under the BELCHER trademark. While the use of these automated systems will naturally have a tendency to reduce labor costs, they are expensive, thereby requiring a long period of effective use before any financial savings are appreciated.
Because of the expense of fully automated pallet assembly systems, there has been a major effort in developing a pallet assembly apparatus which permits more efficient assembly of pallets than is possible with a simple jig, yet which does not involve the expense of a fully automated system. One such attempt is disclosed in U.S. Pat. No. 4,235,005 to James. This patent covers a pallet assembly apparatus having a rotatable table which permits both the top and bottom deck boards to be fastened to the stringers without requiring the pallet to be removed from the table until fully assembled.
While James' apparatus eliminates some of the labor involved in the use of a simple jig, it normally requires two persons to use it, with one standing on each side of the assembly table. There are other drawbacks in the design of the James apparatus. For example, the pallet stringers are held in the table during assembly by pads which compress the stringers endwise by the action of a pair of pneumatic cylinders. This requires constant compression which must be sufficient to hold the stringers adequately but should not be so great as to damage the apparatus components or the stringers. Another drawback with James' apparatus is that it has a substantial number of parts, many of which are by necessity adjustable to permit the apparatus to assemble pallets of different dimensions. It is also desirable with the James apparatus to have a so-called pattern pallet to permit accurate adjustment. The method of using the James apparatus has the drawback of including two separate nailing operations, separated by an intermediate assembly step in which additional boards are mounted in place. This can be inconvenient to the laborers because nailing is typically performed by pneumatic guns, which must be put down for the intermediate assembly step.
Hence, it is a primary object of the present invention to provide an improved apparatus and method for assembling pallets which effectively and reliably overcome the aforementioned drawbacks and limitations of the prior art proposals. More specifically, the present invention has as its objects:
(1) To develop a pallet assembly apparatus which is usable by a single laborer having a minimal amount of skill and training;
(2) The provision of a pallet assembly apparatus which permits the assembly of pallets at a high rate of speed, yet which is relatively simple in design and is therefore inexpensive and easily maintained;
(3) To provide an apparatus for assembling pallets of varying sizes and number of boards and which is easily adjusted to assemble such different types of pallets and which is particularly suited to be easily adjusted to assemble a few different standard sized pallets;
(4) The development of a system for holding pallet components in a pallet assembly table during assembly, which securely holds the components, yet which requires a minimum amount of holding force; and
(5) To provide a method of assembling pallets which does not require the use of expensive, high technology equipment.